NASA scrubs Atlantis launch under storm threat

Atlantis will be rolled back from the launch pad and into its shelter Tuesday morning "unless something really extraordinary happens" with Ernesto's path and intensity, the space agency said.

Ernesto weakened to a tropical storm Sunday, but forecasters warned the storm could regain hurricane status as it moves over Cuba and north toward Florida. (Full story)

If the shuttle leaves its launch pad Tuesday, liftoff would be pushed beyond a September 7 deadline imposed so that the Atlantis mission would not interfere with a Russian Soyuz flight to the international space station in mid-September, said LeRoy Cain, NASA's launch integration manager.

Discussions are under way with Russian officials that could change that deadline and allow the shuttle to begin a mission before its launch window closes on September 13.

Atlantis' next launch window would not open up until October 20, Cain said.

"We are firmly on the path to rollback, but there are two more chances in the rollback scenario where we can say, 'Stop, we're not really coming off the pad because this storm has changed,' " said NASA launch director Mike Leinbach.

But "unless something really extraordinary happens," he said, the Atlantis and its launch vehicle -- weighing 12 million pounds -- will start the slow ride back to the vehicle assembly building at 8 or 9 a.m. ET Tuesday to avoid the likely storm.

Until then, NASA workers will be busy removing the fuel and explosives used in the launch.

Atlantis was set to lift off Sunday afternoon but was delayed while engineers checked the spacecraft for possible damage from a lightning strike Friday. That issue has been resolved, Cain said.

The shuttle crew remained in quarantine Monday waiting for word on the shuttle schedule. It is likely the crew pilots will be put to work flying T-38 jets, training aircraft configured to simulate shuttle flight, back to NASA headquarters in Houston, Texas, ahead of Ernesto's arrival, Cain said.

NASA hurricane guidelines call for the shuttle to be moved off the launch pad if peak winds are forecast to reach 70 knots (79 mph). It must be moved to the assembly building before winds reach 40 knots (46 mph), and there must be no lightning within 20 nautical miles.

The Atlantis flight is the first shuttle mission since the 2003 Columbia crash to deliver a major new portion of the international space station.

Once docked with the space station, astronauts will conduct three spacewalks to install a second set of solar arrays to the station. That should double the station's power capability and add more than 17 tons to its mass. The solar arrays have been packed away since May 2003, when they were originally scheduled to be delivered to the station.